chroma-core/chroma-swift/chroma-swift

Chroma Expert Skill

Overview

Use this skill when working on Chroma architecture, Chroma APIs, Chroma retrieval quality, or operational concerns. It is optimized for this repository (chroma-swift) and also includes upstream Chroma best practices.

Primary goals:

• Build correct, repeatable ingestion and retrieval workflows.
• Keep collection design and embedding strategy coherent.
• Improve retrieval quality before adding complexity.
• Prevent common operational failures (WAL growth, fragmentation, missing auth/TLS).

When to Use

Activate this skill when the task includes any of the following:

• Chroma collections, vectors, metadata, filtering, or similarity query design
• ingestion/upsert/update/delete workflow design
• embedding model selection and dimension planning
• retrieval debugging and relevance tuning
• Chroma performance tuning and maintenance
• Chroma auth, TLS, tenancy, or production hardening
• implementing or reviewing chroma-swift usage

Source of Truth Order

1. Local repository source and tests
2. Official Chroma docs (docs.trychroma.com)
3. Official Chroma Cookbook (cookbook.chromadb.dev)
4. Upstream Chroma repository docs/issues when needed

If sources conflict, prefer local code behavior for this repo.

Workflow Decision Tree

1. Identify runtime mode:

• Ephemeral / in-memory
• Persistent local storage
• Remote/server or cloud deployment

1. Identify problem type:

• Data modeling
• Ingestion correctness
• Retrieval quality
• Performance/operations
• Security/multi-tenancy

1. Apply the matching playbook:

• Use references/chroma-task-playbooks.md

1. Validate using checklists:

• Design checklist
• Query/relevance checklist
• Production checklist

Core Principles

• Keep one embedding model and one vector dimension per collection.
• Use deterministic IDs when idempotency matters.
• Keep metadata schema intentional and stable.
• Use metadata/document filters to narrow scope before ranking.
• Request only needed fields in include to reduce payload and overhead.
• Treat maintenance (WAL pruning, index defrag) as routine operations.
• Never deploy public endpoints without authentication and TLS.

Design Checklist

• Collection purpose is single-purpose and explicit.
• Embedding model choice is documented.
• Embedding dimensions are verified end-to-end.
• ID strategy is chosen (UUID/ULID/hash/semantic key) and justified.
• Metadata keys, value types, and filter intent are documented.
• Distance metric (l2, cosine, ip) is selected intentionally.

Ingestion Checklist

• Input arrays are length-aligned (ids, documents, embeddings).
• Batch size respects runtime limits.
• Upsert vs add semantics are chosen deliberately.
• Duplicate/failed writes are handled idempotently.
• Backfills/re-ingests have versioning strategy for embeddings/model changes.

Query and Relevance Checklist

• Start with simplest working query, then add filters.
• Restrict candidate space with metadata/document filters when possible.
• Verify nResults and fallback behavior when corpus is small.
• Ask only for fields you need in include.
• Evaluate with a small benchmark set of known-good query/answer pairs.

Production Checklist

• Persistence path and backup strategy are set.
• WAL pruning is scheduled and tested.
• Index defragmentation process exists for update-heavy collections.
• Auth and TLS are enforced for any external access.
• Migration policy and rollback plan are documented.
• Observability (logs/traces/health checks) is present.

Repository-Specific Guidance (chroma-swift)

Use these facts as hard constraints for code in this repo:

• Public API surface comes from Chroma/Sources/ChromaSwift.swift.
• Metadata writes are currently restricted:
• Chroma.addDocuments(..., metadatas: ...) throws if any metadata entry is non-nil.
• See ChromaMetadataError.metadataWriteUnsupported.
• AdvancedGetResult.decodedMetadatas() is the intended decode helper for metadata JSON strings.
• ChromaEmbedder requires loadModel() before embed(...) calls.
• ChromaEmbedder batches internally in chunks of 32 texts.
• Tests indicate createCollection(name:) is idempotent by name.
• Tests cover getCollection(collectionName:) for existing and nonexistent collections.

Full repo notes: references/chroma-swift-api-notes.md.

Execution Guidance for Agents

When implementing changes:

1. Confirm mode (ephemeral/persistent/remote).
2. Confirm embedding strategy and collection schema.
3. Implement smallest correct path first.
4. Add tests for:

• idempotency
• filter behavior
• include-field behavior
• concurrency behavior when relevant

1. Document assumptions and operational impacts.

When reviewing code:

• Prioritize correctness and retrieval behavior regressions.
• Flag schema drift and embedding/model mismatch risks.
• Flag missing security controls on networked deployments.
• Flag missing maintenance procedures for persistent deployments.

References in This Skill

• Official best practices: references/chroma-official-best-practices.md
• Repo-specific API and constraints: references/chroma-swift-api-notes.md
• Task playbooks and checklists: references/chroma-task-playbooks.md
• Source index: references/source-index.md